Field of the Invention
The present invention relates to radiographic image capturing systems, in particular, to a radiographic image capturing system that transfers data from a radiographic image capturing apparatus through a wireless network.
Description of Related Art
Radiographic image capturing systems have been developed that capture radiographic images with radiographic image capturing apparatuses (flat panel detectors) each including multiple radiation detecting elements (see multiple radiation detecting elements 7 in FIG. 2, which will be described below). Each radiation detecting element generates electric charges in proportion to the dose of radiation emitted. The radiographic image capturing apparatus reads the electric charges as signal values. The radiographic image capturing system transfers the signal values read at the radiographic image capturing apparatus to a console which generates a radiographic image based on the signal values.
The signal values may be transferred from the radiographic image capturing apparatus to the console through a wired network, i.e., over a cable connecting the radiographic image capturing apparatus and the console, or through a wireless network.
For example, imaging is performed with the radiographic image capturing apparatus in an imaging room in a facility, for example, a hospital, or in a sickroom to which a medical cart equipped with the console and a radiation generating apparatus and the radiographic image capturing apparatus are moved, as described below. During the imaging, the radiographic image capturing apparatus and the console may be connected with a cable. Such a connection, however, may cause a radiological technician to stumble over the cable, precluding smooth imaging. To avoid this problem, the communication between the radiographic image capturing apparatus and the console is performed through a wireless network in many cases.
In recent years, much more opportunities are available to use wireless communications in medical equipment, in-hospital equipment, such as radiology information systems (RISs), or in-hospital networks. During a wireless transfer of the signal values from the radiographic image capturing apparatus to the console, as described above, such circumstances often cause interference between the transfer of the signal values and wireless communications from other equipment in a channel used to transfer the signal values.
For example, Japanese Patent Application Laid-Open Publication No. 2015-58077 discloses a radiographic image capturing system which identifies a wireless communication device that causes interference with signal values transmitted from a radiographic image capturing apparatus (referred to as an “electronic cassette” in this Patent Literature). If such a wireless communication device is identified, the radiographic image capturing system restricts the communications from the wireless communication device to prioritize the transfer of the signal values from the radiographic image capturing apparatus to the console. The restrictions of communication include, for example, stop of communications, restriction of the data rate (i.e., the volume of transferred data per unit time), and channel switching.
Actually, it is not so easy to restrict communications from other wireless communication devices to prioritize the wireless transfer of the signal values from the radiographic image capturing apparatus to the console in many cases, as described above. For example, IEEE802.11a, a wireless LAN standard, requires to avoid interference with radio waves from predetermined radar, such as a weather radar, through dynamic frequency selection (DFS), in other words, to take action to avoid interference with detected interference waves from radars.
Unfortunately, Japanese Patent Application Laid-Open Publication No. 2015-58077 cannot successfully restrict interference waves from a predetermined radar when such interference waves are detected during the wireless transfer of the signal values from the radiographic image capturing apparatus to the console, for example, over a 5 GHz band channel.
Many hospitals and other medical facilities preliminarily select non-overlapping channels in the 2.4 GHz or 5 GHz band and use these channels to perform wireless communications over a wireless LAN between in-hospital medical instruments or devices on in-hospital networks.
For example, during imaging in the imaging room in the hospital or the like as described above, various wireless communication devices other than the in-hospital medical equipment or those on the in-hospital networks may perform wireless communications over various channels in the vicinity of the imaging room. Despite the selection of channels used for communications between different medical instruments to avoid an overlap of channel frequencies, as described above, the channel frequencies for the medical instruments in the imaging room may overlap with those for wireless communication devices other than the medical instruments used in the vicinity of the imaging room, causing radio interference.
For example, during imaging in a sickroom to which the radiographic image capturing apparatus and a medical cart equipped with the console and the radiation generating apparatus are moved, as described above, another wireless communication device may also perform wireless communications in the sickroom or in the vicinity thereof over various channels. This situation may result in an overlap of channel frequencies between the medical instruments and another wireless communication device, resulting in radio interference.
In particular, these issues become more problematic when the medical cart equipped with the console is moved to different sites in a hospital for imaging. The channels used by wireless communication devices other than the medical equipment vary, depending on in-hospital places. This means that channels causing radio interference also vary, depending on in-hospital places. More specifically, a wireless transfer of signal values from the radiographic image capturing apparatus to the console over a particular channel in one in-hospital site (for example, a sickroom) may not cause radio interference, while a wireless transfer of the signal values over the same channel in the other site to which the medical cart is moved may cause radio interference with other wireless communication devices.
For example, during the transfer of the signal values from the radiographic image capturing apparatus to the console, the channel used to transfer the signal values may have radio interference with other wireless communication device. Such radio interference may require the channel used to transfer the signal values from the radiographic image capturing apparatus to the console to be switched to another channel. Such channel switching normally involves a temporary suspension of the transfer of the signal values for about one minute.
Unfortunately, a radiological technician may fail to notice such channel switching. Such a failure may hinder the operations of the radiological technician because the radiological technician does not know the reason why the transfer of the signal values is being suspended. The radiological technician may mistakenly believe that the cause of the suspension of the transfer lies in a defect of the system and perform an unnecessary operation or processing, which may prevent a proper implementation of operations.